Metal fireplace structures with air supply means for combustion chamber



Apnl 27, 1965 H. GRUSHKIN 3,180,332

METAL F EPLACE STRUCTURES WITH AIR SUPPLY NS FOR COMBUSTION CHAMBERFiled April 30, 1962 2 Sheets-Sheet 1 FIG. 2

INVENTOR: HARRY GRUSHKIN BY I J ATT'YS April 27, 1965 H. GRUSHKIN'3,180,332 METAL FIREPLACE STRUCTURES WITH AIR SUPPLY MEANS FORCOMBUSTION CHAMBER Filed April 30, 1962 2 Sheets-Sheet 2 FIG. 5

INVENTOR.

HARRY GRUSHKIN so Y ATT'YS United States Patent Filed Apr. 30, 1962,Ser. No. 190,958 3 Claims. (Cl. 126- 121) This invention, in general,relates to improvements in I fireplace structures and more particularlyrelates to fireplace structures embodying means for supplying outsideair instead of room air to the fireplace to support combustion. v

Virtually all houses in cool and cold climates today are heated by acentral heating system. The fireplace has been outmoded by these moreetficient central heating systems. However, the fireplace is still apopular feature in homes for its aesthetic qualities. These fireplacesburn fuel with combustion, air drawn into the fireplace from the room.

Such fireplaces actually place an added burden on the central heatingsystem of the home because the room air drawn into the fireplace andvented up the chimney is replaced by outside air drawn into the homethrough cracks and openings about windows, doors, etc. In many cases,the cold air drawn into the home exceeds the useable heat output of thefireplace. Furthermore, rooms which are not heated by the fireplacechill quickly because of the cold air drawn through crevices andopenrings in these rooms into the home to replace the air vented up thefireplace chimney.

This invention has as one of its primary objectives the provision offireplace structure which alleviates the aforesaid conditions duringfireplace usage. This is achieved by incorporating into the fireplace astructure or structures through which most or all of the air consumed bythe fire and air drawn into the chimney with [flue gases is suppliedthrough said structure or structures, which in turn are connected bysuitable ductwork to an outside source of air.

These structures are preferably metal shell structures having metalwalls of sufiicient strength to permit their being built in as a part ofthe firewall of the fireplace, in accordance with one type of embodimentof the invention. In another type of embodiment of the invention, thestructures are made as a component part of a metal shell or shells ofthe type wherein cool room air is drawn into a lower part of theshell(s), heated therein by the hot shell surfaces, and discharged intothe room as warmed 'all.

Another primary objective of this invention is to provide structuresused in the construction of fireplaces to improve the elficiency offireplace operation by supplying air to one or more openings in thefirewall of the fireplace through air supply passages having a wall inthe firewall of the fireplace so that cold, outside air is warmed by theheat of combustion in the fireplace before reaching the combustion Zone.

This objective is achieved by utilizing a structure or heater-typefireplace embodying in its metal shell structure a combustion air-supplyunit for the fireplace.

FIG. 2 is a cross-sectional view of the embodiment of FIG. 1 taken onsection 22 of FIG. 1.

FIG. 3 is an enlarged, cross-sectional view of the lower fragment ofembodiment of FIG 1 taken on section 33 of FIG. 2.

FIG. 4 is an enlarged, cross-sectional view taken on section 4-4 of FIG.3.

:FIG. 5 is a cross-sectional view ofthe embodiment of FIG. 1 taken onsection 55 of FIG. 2.

FIG. 6 is a rear perspective view with a fragment of the rear wallbroken awayof the embodiment of FIG. 1.

FIG. 7 is a cross-sectional view of a fireplace showing anotherembodiment of the invention with a portion of the structure broken awayto facilitate illustration of the embodiment. 2

Referring first to FIGS. l-6, the fireplace 1 comprises a hearth 2,facework 3 and mantle 4 of any desired, suitable construction andmaterials. The firechamber of the fireplace is a three-sided, open frontenclosure com-prising metal walls 5, 6 and 7. These metal walls are apart of a prefabricated metal shell adapted to be set in place in abuilding structure provided for it. The front part of the firechamber ofthe prefabricated metal shell has metal top wall 8 bridging the walls 5and 7. The rear portion of the firechamber has a flue 9 made froma'metal, front flue wall 10 attached to or integral with the top wall 8,a pair of side flue walls 11,12 which are integral with or attach-ed tothe rear portionsof the firechamber side walls 5, 7, respectively, and arear structures having a metal wall of an air passage or passages builtinto the firewall of the fireplace so that the metal wall becomes heatedby the fire and warms air passing therethrough.

A still further objective of the invention is to provide metal shell,fireplace air-supply structures which can be readily built into thefirewall of a fireplace, be it a fire- Ibrick wall or a prefabricatedmetal firewall.

These and other objectives and advantages of the invention inherenttherein or hereinafter described may be achieved by practice of theinvention in accordance with the illustrated embodiments thereof in theaccompanying drawings wherein: i

. FIG. 1 is a perspective view-of anair-conduction,

'erals have been used to designate like parts.

line Wall 13 integral with the rear wall 6 of the tire: chamber.

The sides of the prefabricated metal shell have hollow chambers 14, 15.Hollow chamber 14 is defined by side wall 5, an opposing, metal wall 16, a rear wall 17 which is an extension of fire chamber rear wall 6, afront wall 18, a bottom wall 19 spaced above the bottom of the metalshell unit, and a top wall 20. These walls are formed and attachedtogether in any suitable manner so as to form the hollow chamber .14. al

The hollow chamber 14 has ou-twardly directed duct members 21 and 22adjacent the bottom and top of chamber 14. These duct members extendthrough a side wall of the fireplace facework and open into the room.The openings in the fireplace face work may be covered by grillwork 2 3such as shown in FIG 1. These ducts allow room air to circulate throughthe hollow chamber 14 by convection, the air therein being heated by thewall(s) of the chamber which in turn is heated by the fire in thecombustion chamber. Room air is drawn into the chamber 14 through thelower duct 21, and the warmed air is discharged through upper duct 22.

The chamber 15 is constructed similarly to the chamber 14 on theopposite side of the firechamber and like num- The structures of theheating chambers 14, 15 herein disclosed are shown primarily forpurposes of illustration. The convection principle for heating room airby fireplace fires is well known, and any structure utilizing theseprinciples may be used in the practice of the invention in lieu of theillustrated structure for the hollow chambers 14, 15. Other structureswhich may be used in the practice of the invention may be found, forexample, in

'U.S. Patent Nos. 2,080,323; 2,494,527; 2,705,488;

'turcated air passagestructure for conducting combustionsupporting airto the firechamber. This bifurcated strucis ture is located in the loweror bottom portion of the metal shell structure so that thecombustion-supporting air is supplied to the firechamber adjacent thechamber floor and is drawn into the fire zone by the draft of thefireplace.

This feature of the invention comprises, in the embodiment of FIGS. 16,a hollow, metal wall duct 25 extending across the bottom of the rearwall 6 on the rear face thereof. The duct 25 is formed by walls 26, 27and 28 and the rear face of the lower portion of the rear wall 6 of thefirechamber. The ends of the duct 25 are closed by plate segments 29which project rearwardly from the lower, rear edges of the plates 16.Two air passages 30, 31 connect to and project forwardly from the duct25. Each passage 36, 31 is formed by a bottom wall 32, the lowerportions of firewall or 7 and the lower portion of the outer side wall16 of the shell, and the wall 19. The walls 19 are divider wallsdividing passages 30, 31 from chambers 14, 15, respectively. p

The metal shell of FIGS. 1-6 is constructed for use in a chimneystructure located on an outside wall of the building. The supply ofoutside air to passages 25, 30 and 31 is through a short duct 33communicating with and extending rearwardly from passage 25 a distancesufficient to extend through the chimney so that its opening 34 isapproximately at the outer face of the chimney. The opening 34 may becovered by a grille 35 or a damper or shutter if the latter are desired.I

There should be in the combustion air supply system one or more dampers,valves, shutters or the like to stop drafts through the air supplysystem when the fireplace is not in use. A convenient place for suchclosure structure is at the outlet of the air supply passage on thefirechamber wall(s).

As an example thereof, there is shown in FIGS. l-6 a pair of closuresover the openings 36, 37 of passages 3t 31. A plate 38 having verticalslots 3? is attached to each of firechamber walls 5, 7. Between the rearface of plate 38 and a pair of angle irons 4t], 41 attached to walls 32,19 is slidably mounted a closure plate 42 having vertical slots 43corresponding to slots 39. A handle 44 is attached by pin 45 to theplate 42. The pin 45 is slidable in a horizontal slot 46 of a guideplate 47 attached to the front face of plate 38. The handle 44 is usedto slide plate 42 to position slots 39 and 43 in the desired alignmentor nonalignment to admit the desired amount of draft air for thefireplace or to close oi? the fireplace air supply when it is not inuse.

The duct 25, its bifurcated passages 30, 31, their closure structure andthe duct 33 may be used without the remaining structure of FIGS. l-6 inconstructing a fireplace of the invention without a convectionair-heating feature. In such case, the ductwork comprising memers 25, 3t31 and 33 can be made of metal sheeting of sufiicient strength so thatit will support the usual firebrick wall of the firechamber of afireplace, which firebrick wall is built on top of duct 25 and passages30, 31 so that the latter become the lower part of the firebrickfirewall of the fireplace. Also, where room permits, the duct 25 andpassages 30, 31 may be located entirely behind the firebrick firewall ofthe fireplace with appropriate, inwardly-directed ductwork to provideopenings in the firebrick sidewalls or" the combustion chamberequivalent to the openings 43 in the illustrated embodiment.

For fireplaces on inside walls of buildings, the duct 33 may be directeddownwardly and may be connected to additional ductwork beneath thesubfiooring of the building. The latter ductwork in turn extends througha wall of the building or its foundation to connect the duct 25 and itsassociated passages 30, 31 to a source of air outside the building.

FIG. 7 shows another form of the invention in which the combustion airsupply unit is built into the firebrick firewall of the fireplace. Thefireplace is of the usual construction-having a combustion chambercomprising a firebrick side wall 50, a firebrick rear wall 51, and asecond firebrick side wall (not shown). The combustion air supply unitin this case is a rectangular, heavy wall metal box 52 which is builtinto the firebrick wall 50. The metal box has a pair of side walls 53, arear wall 54, a top wall 55 and a bottom wall 56. The front wall of thebox 52 is covered with a removable cover plate 57 having vertical slots58.

Cover plate 57 carries a slidable plate by which the slots 58 can beclosed off in the same manner as described with respect to slots 39 ofplate 38 of the embodiment of FIGS. l-6. Hence, the details of thisstructure will not be repeated.

The opposite side wall (not shown) of the fireplace should also have ametal box 52 and associated parts to provide a balanced air fiow to thecombustion chamber. Each box 52 is supplied with outside air by avertical duct 59' opening into the bottom wall 56 of the metal box.Duct(s) 59 is connected by suitable ductwork 60 beneath the buildingfloor 61 and terminates at an outside wall of the building. In someinstances, e.g., homes with an unheated foundation crawl space,unheated, ventilated basements, etc., the ductwork may terminate inthese areas.

It is to the best advantage in the practice of the invention to supplythe combustion air to the combustion chamber through both side walls ofthe firechamber with the air openings in the side walls being toward theopen front of the fireplace. Under these arrangements, an even, easydraft of combustion air is supplied to the fireplace With littleinduction into the fireplace of room air. Cold air is no longer drawninto the house through cracks and crevices, and the over-all effect is abetter performance of the fireplace and a lesser load on the centralheating system of the home. In fact, with a combustion air supply systemof the invention, the open front of the fireplace may have a glass frontor panel to completely separate the room from the firechamber.Especially in cases where the air supply ductwork is so small that ductresistance to air flow through the supply passages and ducts isinadequate under the normal draw of the fireplace, a blower B may beincorporated in the air supply ductwork to assure an adequate supply ofcombustion air to the combustion chamber. 7

, There are many embodiments of fireplace structure in which theprinciples of the invention may be practiced. Furthermore, even in thespecific embodiments shown and described heretofore, structural changesor additions may be made without departing from the spirit and scope ofthe invention. For example, While it is preferred that the opening(s)communicating the firechamber and the combustion-supporting airpassage(s) be in the forward portion of the side wall(s), they may be inthe middle or rear portion of the side wall(s) or even in the rear wallof the firechamber.

The invention is hereby claimed as follows:

1. A metal fireplace structure comprising a firechamber including avertical metal rear wall and two forwardly-extending, vertical metalside walls, metal wall structure defining with each side wall a hollowchamber on each of said side walls of said firechamber, a horizontaldivider wall in each hollow chamber dividing each chamber into separate,upper and lower hollow chamber segments, each upper segment having anair-entry opening in its lower part and an air-exit opening in its upperpart whereby room air may circulate by convection through said uppersegment, each lower segment defining a forwardly-extending air supplypassage extending along the lower portion of the respective side wall,additional metal wall structure defining with the lower portion of saidrear wall a horizontal, air supply passage extending across the lowerportion of said rear wall, the opposite ends of said last-mentioned airsupply passage being open and in communication with the respective airsupply passages of said lower segments, the lower, forward corner ofeach of said side walls having an opening therein communicating theforward portion of the respective forwardly-extending passage with thefirechamber of said fireplace, closure means at said openings adapted toclose said openings when the fireplace is not in use, and duct meanscommunicating with said horizontal air supply passage for supplying tosaid firechamber through said horizontal passage and saidforwardly-extending passages combustion-supporting air drawn from asource outside the room in which said fireplace is located.

2. A fireplace structure as claimed in claim 1 wherein said duct meansis a horizontal, rearwardly-extending duct connected to andcommunicating with the mid-portion of the rear Wall of said horizontalpassage.

3. A fireplace structure as claimed in claim 1 wherein said closuremeans comprises a slotted plate fixedlymounted across each of saidopenings, a slotted closure plate on a face of each of saidfixedly-mounted slotted plates, and means holding each of said closureplates for movement relative to said fixedly mounted plates to alignReferences Cited by the Examiner UNITED STATES PATENTS 737,382 8/03Frederick 126-131 1,196,766 9/16 Elkin 126121 1,250,712 12/17 Thorne126-120 1,430,781 10/22 Ackroyd 126--120 2,103,171 12/37 Nilson 126--1202,497,486 2/50 Barber 126-120 2,725,874 12/55 Payne 126121 2,970,5902/61 Fauser 126121 JAMES W. WESTHAVER, Primary Examiner.

PERCY L. PATRICK, Examiner.

1. A METAL FIREPLACE STRUCTURE COMPRISING A FIRECHAMBER INCLUDING AVERTICAL METAL REAR WALL AND TWO FORWARDLY-EXTENDING, VERTICAL METALSIDE WALLS, METAL WALL STRUCTURE DEFINING WITH EACH SIDE WALL OF HOLLOWCHAMBER ON EACH OF SAID SIDE WALLS OF SAID FIRECHAMBER, A HORIZONTALDIVIDER WALL IN EACH HOLLOW CHAMBER DIVIDING EACH CHAMBER INTO SEPARATE,UPPER AND LOWER HOLLOW CHAMBER SEGMENTS, EACH UPPER SEGMENT HAVING ANAIR-ENTRY OPENING IN ITS LOWER PART AND AN AIR-EXIT OPENING IN ITS UPPERPART WHEREBY ROOM AIR MAY CIRCULATE BY CONVECTION THROGUH SAID UPPERSEGMENT, EACH LOWER SEGMENT DEFINING A FORWARDLY-EXTENDING AIR SUPPLYPASSAGE EXTENDING ALONG THE LOWER PORTION OF THE RESPECTIVE SIDE WALL,ADDITIONAL METAL WALL STRUCTURE DEFINING WITH THE LOWER PORTION OF SAIDREAR WALL HORIZONTAL, AIR SUPPLY PASSAGE EXTENDING ACROSS THE LOWERPORTION OF SAID REAR WALL, THE OPPOSITE ENDS OF SAID LAST-MENTIONNED AIRSUPPLY PASSAGE BEING OPEN AND IN COMMUNICATION WITH THE RESPECTIVE AIRSUPPLY PASSAGES OF SAID LOWER SEGMENTS, THE LOWER, FORWARD CORNER OFEACH OF SAID SIDE WALLS HAVING AN OPENING THEREIN COMMUNICATING THEFORWARD PORTION OF THE RESPECTIVE FORWARDLY-EXTENDING PASSAGE WITH THEFIRECHAMBER OF SAID FIREPLACE, CLOSURE MEANS AT SAID OPENINGS ADAPTED TOCLOSE SAID OPENINGS WHEN THE FIREPLACE IS NOT IN USE, AND DUCT MEANSCOMMUNICATING WITH SAID HORIZONTAL AIR SUPPLY PASSAGE FOR SUPPLYING SAIDFIRECHAMBER THROUGH SAID HORIZONTAL PASSAGE AND SAID FORWARDLY-EXTENDINGPASSAGES COMBUSTION-SUPPORTING AIR DRAWN FROM A SOURCE OUTSIDE THE ROOMIN WHICH SAID FIREPLACE IS LOCATED.